Definite-pick-up induction relay



May 26, 1925.

- C. l. HALL DEFINITE PICK-UP INDUCTION RELAY Filed March 15, 1923 2 Sheets-Sheet l H r wm o m f r L m n t w ma s C. l. HALL DEFINI'IE PICK-UP INDUCTION RELAY 2 SheetsSheet 2 Filed March 15, 1923 HERB CUR/WENT lnx/erwbor- 3 Chester- IgHalh y His Attorney- CHESTER I. HALL, OF FORT WAYNE, INDIANA, ASSIGNOR '10 GENERAL ELECTRIC COMPANY, A CORPORATION OF NW YORK.

DEFINITE-PICK-UP INDUCTION RELAY.

. To all whom itmay concern:

Be it'known that I, CHESTERI. HA1.I., a

citizen of the United States, residing at Fort iV-ayne, county of Allen, State of- Indiana, have invented certain-"newanduseful Impovements in Definite-Pick-Up Induction Relays, of .whichthe following' is a specification.

The. invention relates to .devices which? cause some desired action" to bedelayed for. an interval of time after the initiation-of a certain of a shifting magnetic field actuates 'cir cuit breaking devices, and m. which the actuation of the circuitbrealnng devices 1s thereby delayed for an'interval of time which is aninverse function of the current in the overloaded circuit.

' One of the objects'of this invention is to secure a' definite pick-up time as small as -may be desired. By this is meant that the period for whichthe actuation of the circuit breaker is delayed shall have some definite and reasonably small finite value for the minimum current value whichwill actuate the relay. -This minimum'current is known as the pick-up current. In most devices of i this character of the prior artthetime of operation at the pick-up point is necessarily an infinite one, and in those devices the time of operation is necessarily-very'large for currents which are only'sligh tlyjn ex-; cess of the Pickup-current.

the relay at the pick-up point which characterizes those devicesin which the time interval of the relay'at 'thepick-up point is infinite. w

A further objectlof this invention is to A still further object is toprovide means which firmly hold the disk in initial posi- "tion when thecurrent in the line isbelow the pick-up point, and other means for rendering such holding means inactive when the current reaches the plck-up'po-int.

Further objects will appear from the condition. More particularly, it has to do with-inverse time limit inductionrelays of that type in which the rotation of a disk of conducting material by means tion of the invention following specific description and explana- In the drawing,"Fig. 1 is a diagrammatic perspectiveof apparatus embodying my invention in a" form adapted to serve as an overload circuit-protecting relay; Fig.

2 shows curves of time with respect to ourrent,-which characterize'a relay embodying this inventionyand also in dotted'lines such curvesior' relays in which the time at the .pick-up point is infinite and Fig- 3 shows diagramma-tically a similar relay with a different arrangement of operating circuits.

Upon lthedrawin'gs, 1 is a disk of conducting material mounted on the rotatable shaft 2 which carries an arm. 3 normally resting against the stop 4, but adapted when the disk has been rotated a certain amount to close a circuit through the contacts 5, 6, to operate a circuit breaker (not shown) or effect any other desired action.

- A shaded pole electromagnet 7 is adapted, when energized by an alternating currentin its coils, to produce a shifting magnetic flux through the disk land generate atorque tending to .rotate this disk. in the direction indicated by the arrow appearing thereon. Another shaded pole electro-magnet 8 is adapted when energized to produce a torque 5 upon" the disk 1 tending to rotate it in the opposite direction. A permanent magnet 9 embraces the disk. A weak spring 10 is adapted to return the disk to initial position, with the arm 3 resting against the stop 4, upon the deenergization of the magnet 7 V I The disk 13 is also of conducting material Another ob ect of this IIWGIHZIOII 1s to -tandjis mounted upon a rotatable rod 11.

avoid the wavering and uncertain action ofj'Theshaded pole electro-Inagnet 12 produces a torque tending to rotate the disk 13 in the.

14 is brought to bear upon the contacts 18,

19. The line 20' represents a portion of the circuit from which the relay 'is actuated. This circuit may be the circuit which is protected by a-circuit breaker actuated upon the closing of the circuit through the contacts 5 and '6. a

In the structure shown in Fig. 1 when 7 reaches the contacts 18 and 19, a circuit is closed-between the terminals of the trans-- former 21 as follows :wire 22, coil of elec the arm 14 is in the position shown in the figure which position may be called the initlal position, a circuit is closed from the transformer 21 through the wire 22, and the coil of the electromagnet 12, wires 23 and 24, arm 14, wires 25, 26 and 27, the coils ofelectromagnet 8 and wire 28 back to the transformer 21. \Vhen the current in the coil of the electromagnet 12 is sufficiently strong to cause the torque exerted by said magnet on the disk 13 to exceed the countertorque of the spring 17, the disk 13 is rotatedand the arm 14 brought against the contacts 18, 19. Vhen the arm 14 leaves-the-contacts 15, ,16 and before it reaches-the contacts 18, 19, a circuit is closed between the terminals of the transformer 21 as follows: wire 22, coil of electromagnet 12, wire 23, coils of electromagnet 7, wires 26 and 27, coils of electromagnet 8 and wire 28. When the arm 14 troma'gnet 12, wire 23, coils of electromagnet 7, wire 26, arm 14, wires 29 and 28.

The spring 17 and electromagnet 12 are so proportioned as to cause the disk 13 to remain at rest with the arm 14 against the contacts 15, 16 as long as the current in the line 20 is weaker than that current at and above which an operation is desired of the circuit breaker or other device which is-operated by the closing of the circuit through the contacts 5, 6. When the arm 14 is in its initial position against contacts 15, 16,

the electromagnet 7 is short-circuited, and

the elect-romagnet 8 is ener ized to firml hold the disk, 1 in its initia position with the arm 3 against the stop 4. The spring 10 also tends to hold the disk 1 and arm 3 in this position, but this spring is preferably made so weak that it is desirable to provide the electromagnet 8 to insure that the disk 1 and arm 3 are maintainedin their initial position until an overload occurs.

Whenever the current in the line 20 rises. to the pick-up value, or to any value in excess ofthe pick-up value, the electromagnet 12 exerts a torque upon thedisk 13 in excess of the torque of the spring 17. This causes the arm 14 to quickly pass to the contacts a 18, 19. When a circuit is thus closed through the contacts 18, 19, the electromagnet 8 is short-circuited'and the electromagnet 7 is energized. The disk'l is thereupon rotated at a'velocity which depends upon the magnitude of the current in the line 20 and upon the strength and adjustment of the permanent magnet 9 as well as upon the design and adjustment of the electromagnet 7 and of its shaded poles. The spring 10 is so Weakas to have no substantial effect upon the speed of the disk.

A circuit through the contacts 5, 6 is of its shaded poles, and is substantially in' dependent of the spring 10.

In various prior art disk relays the pickup point is determined by the strength of the spring or weight which returns the disk to its initial position. torque tending to turn the disk at the pickup point is only infinitesimally larger than the counter torque of the spring; the speed of the diskis infinitesimal and the time of operation of the relay is infinite. In such relays practically no control over the time of action for very small overloads can be exercised in the design or adjustment of the instrument because the counter torque of the spring or weight must be substantially as great as the torque of the means which efl'ects the rotation of the disk when the current is at the pick-up value. In the device herein described the counter, torque of the spring 10 is of negligible effect compared to the torque of the magnet 7 when the current In such devices theis at the pick-up point. In fact the magnet of the characteristic curves for different designs or adjustments of a relay which'has an infinite time of action at the pick-up point. fulllines two curves C and D as examples of the kind of variation of the time of action with respect to current which is possible in such a relay as is disclosed in the present application. The portions of the curves C and D between the zero-current line and the pick-up line are drawn in light lines to indicate that'those portions of these curves to the left of the pick-up point do not represent any actual operation of the relay.

In the device of the present application, the value of the current at which the device picks up is fixed by the strength of the spring 14 and by the strength of the magnet- 12 operating on the disk 13 entirely without regard to the design and strength of the parts which operate upon the disk 1 strength andposition of the magnets 7 and 9 may be so chosen as to give the desired time of operation whenthe magnet 7 is energized made. as small as v In the same figure I have shown in lot The l by the pick-up current. The time-current curve may be given substantially the form of the curve C, Fig. 2, or of the curve D or any other desired form by properly proportioning'the ratio 0f.the counter torque of the electromagnetic flux cutting the disk 1 to the forward torque of such flux and by properly proportioning the el'l'ective strength of the permanent magnet 9 all as explained in my application, Serial No. 614,331, filed January 2 1923. The control of the distance through which the disk 1 is made to rotate to close contacts 5, 6 enables the designer to maintain the time of operation 1 at the pick-up point at any desired value when changing the shape of the curves by the means pointed out in said other application.

Fig 3 shows diagrammatically a modification of the invention. The disks 1 and 13, the electromagnets 7, 8 and 12, the contacts 5 and 6, 15, 16, 18 and 19, and the arms 3 and 1 1, the permanent magnet 9, 'the line 20-and transformer 21, are all the same as in Fig. 1. The only diii'erence is in the wiring. Instead of short-circuiting one or the other of the electromagnets 7,8, according to the position of the arm 14, as in Fig. 1, the modification shown in Fig. 3 is wired to break the circuit through one of these electromagnets when the circuit is closed through the other and vice versa. In this modification, when the current in the line 20 is below the pick-up current a circuit is closed between the ends of the transformer 21 through the wire 31, coil of electromagnet 12, wire 32, arm .14, wire 33, coil of electromagnet 8 and wire 34. WVhen the current in line 20 exceeds the pick-up current the arm 14 closes the circuit between the contacts 18, 19 and breaks the circuit between the contacts 15, 16. A circuit is then closed between the ends of transformer 21 as follows :-wire 31, coil of electromagnet 12, wire 32, arm 14, wire 36, coil of electromagnet 7 and wire 37 and wire 34. In order to insure that the electromagnet 8 is not deenergized before the-electromagnet 7 is energized the arm 14 may be made sufficiently broad as to en gage the contacts 18, 19, before it leaves the contacts 15, 16. The arm 14 wipes the contacts in this form of the invention so that after engaging the contacts 18, 19 it can by further motion become disengaged from the contacts 15, 16.

In the forms ofboth Fig. 1 and Fig. 3, when the disk 1 has completed its journey and connected contacts 5 and 6, and thereby caused the operation of the protective device, the current in line 20 ceases or is reduced. This deenergizes the electromagnets 7 8 and 12 and the disk 1 and 13 are returned to their initial positions by their springs 10 and'17. hen current is reestablished in line 20, the magnet 8 is energized to complete the return of disk 1 to its initial position, if this has not already been of energizing current, means whereby the movable element is not moved until the current exceeds a predetermined strength and is moved with a substantialdefinite velocity as soon as this strength is exceeded no matter how small the excess may be.

2. A time limit device comprising a light, movable member of conducting material, a current-energized motorelement which sends a shifting magnetic flux through said movable member to cause its motion at a speed which varies with the strength of the energizing current, a source of energizing current, means for maintain-,

ing the motor element deenergized until the energizing current exceeds a certain strength and for energizing the same when this strength is exceeded, the movable member being movable at a substantial definite speed as soon as this strength is exceeded no matter how small the excess may be.

A time limit overload relay having in combination a rotatable disk of conducting material, a current-energized moto r element for sending a shifting magnetic flux through said disk to rotate it with a speed which varies with the strength of the energizing current, a source of energizing current, means biasing the disk to its initial position, means for maintaining the motor element deenergized until the energizingcurrent has reached a certain strength. and for energizing the same therewith when this strength is exceeded, the strength of the biasing means being so proportioned to the strength of the motor element as to leave a substantial definite net torque for rotating the disk when the motor element is energized no matter how little the energizing current may exceed the smallest value at which it energizes the motor element.

4. A time limit device comprising a light movable member of conducting material, means operated by said movable member when the same has moved through a fixed distance, a current-energized motor element which sends a. shifting magnetic flux through said movable member to cause its motion at a speed which varies with the strength of when the same has moved through a fixed distance, a current-energized motor element which sends a shifting magnetic flux through said movable member to cause its motion at a speed which varies with the strength of the energizing current, a source of energizing current, means for maintaining the motor element deenergized until the energizing current exceeds a certain strength and for. energizing the same when this strength is exceeded,. the movable member being movable at a substantial definite speed as soon as this strength is exceeded no matter how small the excess may be.

6. A time limit overload relay having in combination a rotatable disk of conducting material, means operated by said movable member when the same has moved through a fixed distance, a-current-energizedmotor element for sending a shifting magnetic flux through said disk to rotate it with a speed which varies with the strength of the energizing current, a source of energizing current, means biasing the disk toiits initial -pos1t1on, means for malntaln -ng the motor element deenergized until the energizing current has reached acertain strength and -for energizing the same therewith when this strength is exceeded, the strength of the biasing means being so proportioned to the strength of themotor element as to leave a" substantial definite net torque for rotating the disk when the motor element is energized no matter how small the energizing current may be. v

7. A time limit overload relay having in combination a conducting disk rotatable throu 'h a predetermined angle, means operated by the disk at the end of its journey, a shaded pole electromagnet for rotating the disk, a spring vbiasing said disk to initial position, a source of current for the shaded pole magnet, a switch for sending said current to the shaded pole magnet, means holding said switch normally ineffective for this purpose, electromagnetic means for rendering said switch efi'ective for this purpose when the energizing current reaches a certaln magnitude, the torquejof the biasing spring for the rotatable disk being substan-' tially less than the torque of the shaded pole magnet when thelatter is energized with the minimum current to.which it may be subjected." v ,8. An inverse time limit device having a having a disk of conducting material, means actuated uponthe rotation of the disk through a predetermined distance, electromagnetic! means, normally deenergized, adapted when energized to send a shifting flux through said disk to rotate it, means continually opposing the rotation of the disk with a torque which is substantially less than thehminimum torque exerted by said electromagnetic means when energized, means actuated when the current in a c1rcuit reaches overload proportions to energize.

said electromagnetic means with a current which is proportional to the current in that circuit.

10. An inverse time limit device comprising a rotatable disk of conducting material, electromagnetic means which when energized rotates the disk at a speed which is a direct function of the energizing current, a second rotatable disk of conducting material, electromagnetic means for rotating said second disk, means opposing therotation of the second disk and preventing rotating thereof until the energizing current in the electromagnetic means which operates the second disk has reached a predetermined value, and means actuated by an advance of the second disk for' energizing the electromagnetic means which operates the first disk.

' 11. An inverse time limit device having a rotatable disk of conducting material, means weakly opposing rotation thereof, electromagnetic means adapted when energized to rotate said disk at a speed which is a direct 'tunctlon of the current which energizes the electromagnetic means, means operated by the'disk when the disk. has rotated a pre determined distance which is relatively long, a second disk of conducting material.

means strongly opposing the rotation of" said second disk, a second electromagnetic means tending to rotate said second disk with a force which is proportional to the current inv said second electromagnetic means, means operated by the second disk, when the second disk has rotated a relatively short distance, to energize the electromagnetic means which rotates the first mentioned disk,

12. A device having a movable member of conducting material, electromagnetic means adapted to send a shifting flux therethrough and to develop a force tending to move the same, a second electromagnetic means acting on said movable member in a direction which is opposite to the direction of operation of the first mentioned electromagnetic means, means for deenergizing said second electromagnetic means upon the occurrence of the condition which makes anvoperation of the movable member desirable. .i

13. An inverse time limit device having a rotatable disk of conducting material, electromagnetic means normally .deenergized and adapted when energized to rotate said disk, means weakly biasing said disk to initial position, a second electromagnetic means normally energized and tending when energized to strongly hold said disk in initial position, and means for deenergizing said second electromagnetic means and for energizing said first mentioned electromagnetic means upon the occurrence of a certain condition.

14. An inverse time limit device comprising' a movable member, a firstelectromagnetic means, normally deenergized and adapted when energized to advance said movable member, a second electromagnetic means normally energized and tending when energized to move said movable member in the reverse direction, and a device which upon the ocurrence of acertain condition,

deenergizes the second electromagnetic means and energizes the first electromagnetic means and which upon the departure of that condition deenergizes the first electromagnetic means and energizes the second electromagnetic means.

15. An inverse time limit overload relay comprising a rotatable disk of conducting material, electromagnetic means normally deenergized, which when energized moves said disk in a forward direction with a speed which is a. direct function of the energizing current, a second electromagnetic means, normally energized which when energized tends to move said disk in the reverse direction, means to protect a circuit operated when the rotation of the disk has advanced a predetermined distance, means operated by the current in the protected circuit when said current exceeds a predetermined value to deenergize said second electromagnetic means and to energize the disk-advancing electromagnetic means with a current which is proportional to the current in the protected circuit.

In witness whereof, I have hereunto Set my hand this eighth day of March, 1923.

CHESTER I. HALL. 

